Packing Under Range Regulations

题目描述

Solve the following problem for $T$ test cases. There are $10^9$ boxes numbered $1,2,\dots,10^9$ and $N$ balls numbered $1,2,\dots,N$.
Each box can contain at most one ball.
Determine whether it is possible to put all $N$ balls in the boxes so that the following condition will be satisfied.

For each integer $i$ from $1$ through $N$, the ball numbered $i$ is in a box numbered between $L_i$ and $R_i$ (inclusive).

输入格式

Input is given from Standard Input. The first line is in the following format: $T$

Then, $T$ test cases follows, each of which is in the following format: $N$ $L_1$ $R_1$ $L_2$ $R_2$ $\dots$ $L_N$ $R_N$

输出格式

Your output should have $T$ lines.
In the $i$-th $(1 \le i \le T)$ line, print $Yes$ if it is possible to put all $N$ balls in the boxes so that the condition will be satisfied in the $i$-th test case in the input, and print$No$ otherwise.
The checker is case-insensitive; it will accept both uppercase and lowercase letters.

2
3
1 2
2 3
3 3
5
1 2
2 3
3 3
1 3
999999999 1000000000

Yes
No

提示

$1 \le T \le 2 \times 10^5$ $1 \le N \le 2 \times 10^5$ $1 \le L_i \le R_i \le 10^9$ The sum of $N$ across the test cases in one input is at most $2 \times 10^5$.This input contains two test cases.

In the $1$-st test case, the following way to put the three balls would satisfy the condition, so we should print $Yes$.

Put Ball $1$ in Box $1$. Put Ball $2$ in Box $2$. Put Ball $3$ in Box $3$.

In the $2$-nd test case, there is no way to put the five balls to satisfy the condition, so we should print $No$.

标签: AtCoder|abc214E

来源

AtCoder|abc214E